(a) Field of the Invention
The invention described herein relates to new and useful compounds classified in the art of chemistry as 1-imino-3-(4-thioxo-5-thiazolidinylidene)isoindolines, to valuable metal chelate pigments derived therefrom and to intermediates and processes for obtaining them.
(B) Description of the Prior Art
Metallized organic pigments of widely diverse structural types are known in the prior art. Among the more important classes of such metallized pigments may be mentioned, for example, metal chelates of: ortho-hydroxy azo pigments as described in U.S. Pat. No. 1,232,551; azomethine metal complex pigments as taught in U.S. Pat. No. 3,687,991; metallized porphyrin pigments as described in Berichte 60: 2611 (1927) [Chemical Abstracts 22: 1163 (1928)]; and metallized porphyrazine pigments as described in U.S. Pat. No. 2,765,308. The closest related prior art appears to lie in the class of pigments known as metallized tetrabenzoporphyrazines of metallized phthalocyanines. These compounds are well known and have been extensively described in Chapter 9 of The American Chemical Society monograph entitled "The Chemistry of Synthetic Dyes and Pigments", edited by H. A. Lubs, Reinhold Publishing Corporation, 430 Park Ave., New York, N.Y. (1955), as well as in many U.S. patents, particularly those in the Patent Office classification 260-314.5 entitled "Phthalocyanines".
There are a number of U.S. patents in the prior art which teach the use of 1,3-diimino-isoindolines as intermediates in the preparation of dyes and pigments. For example, U.S. Pat. No. 3,646,033 teaches the production of asymmetrically disubstituted isoindoline dyestuffs. Specifically disclosed therein is the interaction of 1,3-diimino-isoindoline and 1-phenyl-3-methyl-5-pyrazolone to form 1-[(1'-phenyl-3'-methyl-5'-oxo)-pyrazolidene-4']-3-iminoisoindoline which, in turn, is further interacted to introduce a second substituent in the 3-position forming a compound useful as a dyestuff.